Power-transmitting mechanism



N. R. BROWNYER POWER TRANSMITTING MECHANISM July 1948.

7 Sheets-Sheet 1` Original Filed July 13, 1944 N. R. BRowNYER Re. 23,018

7- Sheets-Sheet 2 EN NN QLIN mw July 27, 194s.

' POWER TRANSMITTING MECHANISM Original Filed July 13, 1944 m n w mm II, N a x @n @n ww N. R. BROWNYER POWER TRANSMITTING MECHANISM July 27, 194s.

Original Filed July l5, -1944 l am N. R. BROWNYER POWER TRANSMITTING MECHANISM Juvly 27, 1948.

original Filed July 13, 1944 'T Sheets-Sheet 4 /Ve/son A- rowng/er @pI/@M w Wm /26 aos July 27, 1948- I N. R. BowNYER Re. 23,018

POWERYTRANSMITTING MECHANIS I Original Filed July 13, 1944 7 Sheets-Sheet 5 fiar/rey.: j@

vJuly4 27, 194s.

Original Filed July 13,` 1944 @zy/2 L N. R. BROWNYER POWER TRANSMITTING MEcHANzsu I INI/Ewan.

Reuued July 27, 1948 Re. 23,018l

:aus Powr-:a-'raANsmr'rrNG MEcnANrsM Nelson R. Brownycr. Birmingham. Mich., assigner to The Timken-Detroit Axle Company. Detroit, Mich., a corporation of Ohio Original No. 2,398,407., dated April 16. 1946, Serial No. 544,716, July 13, 1944. Application for reissue April 15. 1947, Serial No. 741,514

23 Clllml.

The present invention relates to power transmission mechanisms and to controls for such mechanisms and is a continuation-impart of my application, Serial No. 387,977, filed April 10, 1941, for Power transmission mechanism. More par(- ticularly, the invention relates to power operated multiple speed power transmissions incorporated in axles for internal combustion engine powered vehicles, although it is not limited to such use. and may be advantageously employed wherever power is to be selectively transmitted at two or more different speed ratios.

Early manually shifted automotive speed changing transmissions incorporated in multispeed axles comprised comparatively simple me-l chanical toothed clutching devices, but to change their speed ratios without clashing or stripping the gears required much experience and a high degree oi skill and even a skilled operator could not always make a shift without damage to the mechanism.

The diiliculty is greatly increased in two speed truck axles, because of the large rotational inertia.

of the parts involved. 'I'he use of such multispeed mechanism has also necessitated the addi;- tion of con-trol levers to the crowded modern truck cabs, cramping the driving space. and increasing the diiliculties and hazards of driving. In spite of these didlculties, however, such two speed axles have gone into rapidly increasing use in recent years because they may be readily installed in place of standard truck axles, and their use doubles the number of speed ratios obtainable with the conventional truck transmissions only, thus eliminating the need for more complicated multiple speed transmissions in heavy trucking serviceand permitting the low cost conversion o! standard low priced comparatively low powered .trucks for heavy duty use.

y, Early efforts to minimize such shifting dim- .fulties rfollowed the obvious course of trying to y make the meshing of the teeth easier by increasing the clearances between the engaging teeth.-

. chamfering or rounding oil' the tooth corners, ta-

pering the teeth and/or making lalternate engag-L ing clutch teeth long and short, as exempliiied in 1 Patent No. 2,183,667, issued Dec. 19, 1939, to L. R.

Buckendale for Dual ratio drive axle. 'I'hese expedients have failed to solve the problem because y they tend to permit the clutch parts to engage readily before their speeds are synchronized, causing severe jerks and shocks, and subjecting the entire driving train to severe strains resulting in premature failures of the associated parts.

To overcome thesek dimculties, relatively vast sums of money and amounts of time were then spent to develop complicated and costly clutch synchronizing devices to synchronize the clutch parts prior to engagement, and thereby reduce wear and tear on the mechanisms incident to shifting, especially by careless operators. While such synchronizing devices facilitate shifting and have .been generally adopted in conventional types oi automotive transmissions, because of their added complications. and costs, they have not been applied in the two-speed truck axles heretofore on the market.

Recently, however, a demand has arisen for the application of automatic or semi-automatic power shifting mechanisms to two-speed axles which give the driver no opportunity to even attempt, by the exercise of necessary skill, to mesh the gears without shock or clash.

To meet this situation, it has heretofore been.

deemed necessary to incorporate synchronizing devices in power shifted two speed axles, and then to provide complicated delayed action controls to prevent premature engagement of the parts before the synchronizer could become effective, as disclosed in Harper et al. Patent No. 2,071,165, granted February 16, 1 937. This patent shows a power shift embodying a frictional synchronizer clutch and a delayed action control for the vacuum cylinder which causes a predetermined dwell or lag during the shift operation, to permit synchronization to take place. This type of axle has gone into use as optional equipment 'on pleasure cars provided with a control valve interconnected with the clutch pedal to insure'proper shifting. 'I'hese controls are costly, introduce mechanical complications, andr have not as yet gone into standard production for any automotive use'.

Instead of making the clutch members easy to engage, and then providing complicated and costly synchronizing and control devices to prevent premature engagement, I have discovered that by making the interengaging clutch teeth dimcult to engage, through the use of smooth, parallel abutting ends having sharp corners, properly restricted engaging clearances, and properly proportioned engaging and disengaging pressures. toothed clutch constructions may be produced which .can be shifted silently and without shock. either manually or by power means, under any conditions of vehicle speed and load, and without the need of any form of friction clutch. When the clutch members constructed in accordance with my invention are rotating relatively and their parallel tooth ends are brought into engagement with a force whose magnitude bears a proper reditions.

In Maybach Patent No. 1,719,188, granted July 2, 1929, a transmission disclosed allegedly shiftable under certain conditions of relative rotation between the parts, without disengaging .the vehicle clutch. A resilient connection is interposed between the shift lever and the clutch collar, inclined teeth are employed, so that the lever may be shifted at random to pre-select the gear ratio, and Ishift of the clutch allegedly occurs automatically later on by the resilient means, upon synchronism of the parts. The inclined tooth ends of the gears and clutch caused a rattling action to take place until the parts were synchronized. As will be apparent, rapid wear of the sharp inclined tooth corners would occur, and the oneway inclined teeth will grab with a violent shock unless the parts are rotated relatively to each other during the synchronizing operation in the directions disclosed by Maybach. And, as pointed out in Maybachs later Patent No. 1,891,678, the parts of the construction of Patent 1,719,188 did not always properly engage, allegedly due to variations in the throttling of the engine. Maybach proposed to correct this defect in Patent No. ,1,891,678 by interconnecting the throttle and shift mechanism. This resulted in a complicated construction which, so far as I am aware, has not .gone into commercial use.

It is accordingly the primary object of this invention to provide a multi-speed transmission mechanism having a novel shifting assembly which enables the desired speed ratio to be selected at any time, and without requiring disengagement of the vehicle clutch, and which will automatically and silently shift into the selected speed upon momentary interruption of torque delivery.

A further object is to provide a change speed mechanism embodying toothed mating members having parallel tooth ends, together with means for urging them into engagement by forces whose magnitude bears such relation tothe area of the parallel tooth ends, that the latter will smoothly slide upon each other but will not engage until synchronization is `substantially complete.

Another object is to provide a power shift -mechanism embodying members having parallelended confronting teeth and blocking means for positively retaining them in full mesh so long as power is transmitted between them in either direction, and to so proportion the length of the teeth and the area lof their ends that, when a torque interruption occurs, the power shifter will readily disengage the teeth, and when shifted in -the opposite direction the teeth will abut and block completion of the shift until synchronization is effected.

A 'further object is to provide ,a transmission assembly embodying a novel power operated shifting mechanism enabling the desired available gear ratio to be pre-selected at any time during operation and which will subsequently automatically carry out the shift into the pre-selected speed ratio under the control of the operator, but only when the parts are synchronized, without shock. the parts being so designed that it is immaterial which ldirection of relative rotation occurs between them during the synchronizing operation.

A further object is to provide a speed change mechanism with power operated means for selectively shifting it from one speed ratio to another, and having means for automatically shifting it into one speed ratio in the event vof power failure.

A further object is to provide multi-speed axle equipped vehicles with novel control mechanisms for automatically changing the speed ratio of the speedometer drive to correspond to the speed ratio of the axle.

Another object is to provide a two speed shift clutch which is shiftable into mesh with a. pair oi' gears, with a shifting mechanism which will exert a relatively heavy clutch disengaging force vand a relatively light engaging force in which there is a denite staging of pressures or a sharp drop in pressure after the clutch collar has been disengaged from either gear.

A further object is to provide a two speed shift mechanism embodying a clutch collar which is meshable with a pair of gears, and means for exerting positive or non-yielding disengaging forces upon the clutch collar, and for exerting yielding forces of lower magnitude for bringing the clutchV collar -into mesh with the gears, in both directions of shift.

Further objects will become apparent as the specification proceeds in conjunction with the annexed drawings, and from the appended claims.

In the drawings::

.Figure l is a top view of a two speed automotive axle embodying the invention, certain parts being broken away and shown in cross section to more clearly illustrate the construction;

Figure 2 is a fragmental sectional view, taken substantially on the line 2 2 of Figure 1, looking in the direction of the arrows;

Figure 3 is an enlarged longitudinal sectional view of the speed change mechanism of Figure 1, as it appears when removed from the casing, and with the parts in low gear;

Figure 4 is a diagrammatic view showing the cooperating clutch teeth of the collar, the shaft and the drive gears of the mechanism'shownin Figure 1, as they appear when the device is operating in low speed and with the collar locked against shifting;

Figure 4A is a view similar to Figure 4, on a larger scale;

Figure 5 is a view similar to Figure 4, but shows the parts in the position they assume when the collar teeth are .sliding on the clutch teeth of the high speed gear, prior to shifting into high speed;

Figure 5A is a view similar to Figure 5, on a larger scale:

Figure 6 is aview similar to Figure 4, but shows the parts in high gear and with the collar locked` against shifting;

Figure 6A is a view similar to Figure 6, onf' larger scale;

Figure 7 is a diagrammatic view of affra'g'ni tary portion of a vehicle showing a novel control mechanism lconstructed accordingl to the invention appliedV thereto; s Figure 8 is a top plan view supplementing Figure 7, and illustrates the manner in lwhich the controls are associated with the rear axle;

sacra Figure 9 is a side elevational view. on an enlarged scale, of the speedometer change speed gear shown in Figure 7;

Figure 10 is an enlarged sectional view of the vacuum control valve shown in Figure 7;

Figure 1l is an enlarged sectional view ofv the" vacuum operated control mechanism shown in Figure 8;

Figure 12 is a sectional view of a modified valve and vacuum cylinder assembly for controlling the transmission, also forming part of -the invention:

Figure 13 is an elevational view with parts in Asection of a modified speedometer control also forming part of the invention;

Figure 14 is a horizontal sectional view of a planetary axle embodying the invention. showing the parts vin the overdrive position Figure 15 is a diagrammatic sectional view of a fragmental portion of mechanism shown in Figure 14 with the parts in overdrive position;

Figure 16 is a view similar to Figure i5 but shows the parts shifted out of overdrive position,

into neutral position;

Figure 17 is a view similar to Figure 18, but shows the parts as they are about to be shifted into the direct drive position;

Figure 18 is va longitudinal sectional view on an enlarged scale of the shiftable toothed collar shown in Figure 14:

' Figure 19 is a longitudinal sectional view on an enlarged scale of a fragmentary portion of the shift rod shown in Figure 14: and

Figure 20 is a perspective view oi' fragmentary portions cf the mechanism of Figure 14- showingfa modified clutch tooth construction to provide a locking function.

With continued reference to the drawings and particularly to Figures 1 and 3. wherein the improved shifting mechanism is shown embodied in a two speed, double reduction drive axle for an automotive vehicle, the numeral Il indicates the axle housing having an enlarged center portion lila from which the hollow arms Ib and llc extend. The arm IIIb incloses a rotatable axle shaft I I while the arm Iilc incloses a similar shaft i2. Suitable road wheels (not illustrated) are Journalled on the outer ends of the arms IIIb and Ic and the shafts II and i2 are drivin-gly connected to respective wheels in a conventional or desired manner.

movement.

ure 3, has two gear journal on a splined portion 2l' of a cross shaft or counter shaft 22.

Cross shaft 22 has its right angles to the axis of I1 and may, if' desired. be disposed below the propeller shaft section, in which case the gears I2 and 2l would be hypoid gears. The cross shaft is iournalled in the gear carrier case Il by having its reduced end portions mounted in the anti friction roller bearings "2l bearing 22 is mounted in a cap or 22a which has a cylindrical boss portion 22h piloted in an apertured annular boss formed on the side of the gear carrier Il and a bolting flange 22c secured to the boss by suitable bolts or screws (not illustrated). l

The bearing 2l is similarly mounted in a cap or cover member 24a having a cylindrical boss portion 2lb piloted in an apertured annular boss on propeller shaft section the gear carrier and a bolting flange 24e secured to the carrier boss by suitable bolts or screws (not illustrated). The bearings 22 and 24 are capable of taking thrust or axial loads as well as radial loads and'may be adjusted by the caps 22a and 24a to support the cross shaft 22 against endwise The cross shaft 22, as particularly shown in Figportions 22a and 22h separated by an enlarged center portion 2S provided with peripheral clutch teeth later to be described in detail.

As 'a sub assembly the shaft 22 carries, in addition tothe bearings 22 and 42l and the beveled ring gear 2l, a small'diameter spur gear 2l jour- At their inner ends the shafts Il and I2 are operatively connected with a differential mechanism generally .indicated at i2 which may be of the form illustrated and described in Buckendale Patent 2,183,667, referred to above. This dinerential mechanism includes a cage Ila having reduced cylindrical end portions iournalled by anti friction bearings lib and llc in bearing legs Ila and lib formed in a gear carrier case Il in the manner more fully disclosed in the Buckendale Patent 2,183,667 referred to.

The gear carrier case is secured to the enlarged center portion Illa of the axle housing 'by means of suitable bolts or screws passing through the piloted bolting flanges Ilid and Ild.

At its end opposite flange Md carrier case I4 provides an apertured cylindrical boss Ile which receives a piloted bearing cage i5 in which are mounted two spaced anti friction roller bearings lia and IBb which support the axle carried propeller shaft section I1. This shaft has integrally formed on its inner end a beveled pinion gear Il which meshes with a beveled ring gear 2l ilxed nailed on the shaft portion 22a, alarge diameter 'spur gear 21 Journalled on the shaft portion 22h,

and an'internally toothed annular clutch collar 24 slidably mounted on the enlarged shaft portion 2l and selectively 'operatively engageable with the spur gears 2l and `21 in a manner to be later de- .scribed in detail.

When the above described cross shaft sub aslembly is embodied in the operativeassembly shown in Figure l the spur gear 22 constantly meshes with a cooperating spur gear 22 mounted on the differential housing i3d at one end thereof while the gear 21 constantly meshes with a corresponding spur gear 22 mounted on the dinerentiai housing at the opposite end thereof from gear 2l.

From Uhedescription so far it is apparent that when the propeller shaft section I1 is driven by asuitable power engine 1l of Figure 7 driving through the conventional friction clutch III, change speed transmission II2 provided with manual shift lever II'I, propeller shaft lil and universal joints, one of which is illustrated at IIE, the pinion gear Il meshing witfh the bevel ring gear 20 will drive the cross shaft 22 and the clutch collar 24. If the clutch collar is operatively engaged with the gear 2l the drive will continue through the gear 22 and meshing 'gear 2l to the diiferentiai cage or housing Ila and through the differential mechanism to the axle shafts I i and I2, providing a low speed gear drive for the axle. If, on the other hand, clutch collar u is operatively engaged with spur gear 21, the drive which it engages the gear 21. However, if it were axis. substantially at and u. AThe' cover member source, such as the automotive.

will be from the cross shaft .22 through gears 21 and 29 to the differential cage desired to provide for operating the axle as a dead I axle, the arrangement could be modied to provide a third operative position in which the collar would be held in a neutral or centered position out of engagement with both of the gears 25 and 21.

Figures 2 and "I to 12 inclusive show suitable means for selectively engaging the with the gears ,and 21.

As shown in Figure 2 a pin or shaft 49 is rotatably mounted in a bushing 52 secured in a boss 52a formed internally of the gear carrier i4, in

' position such that its axis is at right angles to but offset from the axis of cross shaft 22. Within the gear carrier shaft 49 carries a yoke 49 which partly surrounds the clutch collar 34 and is provided at its ends with swivelled blocks 41a and 41h of T-shaped cross section which extend into an annular groove provided in the outer surface of the clutch collar 34. With this arrangement rotation of shaft 49 will swing the yoke 48 and move clutch collar 34 along shaft 22 between the two operative positions of the clutch collar.

The pin or shaft 49 extends through the top wall of the gear carrier i4 and is provided externally of the carrier with a lever 54 secured thereon by a nut 53. Shaft rotating movements of the lever are limited by a stop finger 55 formed on the vlever and engageable witha pair ofeccentric headed pins 55 and 51. l

When the parts just described are assembled, lever 54 is rocked back and forth to shift the clutch collar into its high and low speed positions, and the positions of the lever for eachshifted position of the clutch collar observed, and .the yoke so located as to dispose blocks centrally with respect to groove 35 and free from rubbing engagement.

, When the high and low speed positions of lever 54-uhave been properly located from the high and low speed positions of the clutch collar, a pair of pins 55 and 51, having eccentric heads, are rotated into proper position to cooperate with finger 35 of the lever and arrest it in the proper positions, and `they are then driven into openings in the housing. Pins and 51 are each provided with a groove and, as they fit the openings rather tightly; when they'are driven in place, the metal of the housing extrudes slightly into the grooves of the pins, thereby permanently locking them against rotation.

It is accordingly apparent that pins 55 and 51 accurately stop the lever in both of theshifted positions and prevent the clutch collar from being frietionally gripped between blocks 45 and either gear 25 or gear 21. l When the parts-are in the positions 'illustrated in Figures 8 and 11, spring 51 maintains lever 54 in low speed position, with iinger 55 of arm 54 abutting stop 51, thereby relieving' the clutch collar of pressure. By adjusting clevis 55, the proper operating relationship between rod 54 and lever 54 may be correctly established.

As shown in Figure 8, a pneumatic device 59,

illustrated in section in Figure 1l, is operatively connected to lever 54 by a pivoted link 54 and is connected to an air pressure or vacuum line 59 which extends to a manually operable valve 15 shown in Figure 7 and illustrated in section in Figure l0. In the arrangement illustrated `the line 55 is a vacuum line and a second vacuum line 14 extends from valve 15 through a check valve 13 to intake manifold 1i of engine 1li. If desired a vacuum tank may be connected with line 14 clutch collar ing on the diaphragm when the chamber within" casing 59 back of the diaphragm is subjected to less than atmospheric pressure through vacuum line 59. The spring 51 has characteristics such that the rst part of the movement of the diaphragm from either end of the casing is accomplished with a much greater force than the last part of such movement for a purpose which will be explained in detail hereinafter in connection with the description of the novel clutch structure.

Movement of the diaphragm 52 is controlled by the manually actuated valve 15, which may be a plunger type valve as illustrated or may be a rotary or other type valve as may be desired.

which passes the slidable valve stem 19. Upon its inner end the stem 19 carries a spool shaped plunger 11 having end piston portions which closely t the bore 15 separated by an intermediate reduced portion 19. i

The plunger has two operative positions, as

indicated by the fun and broken unes 1n Figure 10. When in the f ull line position the vacuum line 68 is connected with the atmosphere through port and spring 51 moves diaphragm 52 and link 54 to the position illustrated'v in Figure 11, rotating shaft 49 to shift clutch collar 34 to its low speed position in which it operatively engages gear 26.

When plunger 11 is in its broken line position, as shown in Figure 10, vacuumy line 55 is conneet-ed through the reduced intermediate portion 19 with vacuumv line 14 whereby, -if engine '-lli is operating. vacuum will be applied to the back of diaphragm 52 to move the diaphragm against the force of spring 51. This will rotate shaft 49 and shift clutch collar 34 into its high speed position in which it is in operative engagement with gear 21.

Valve stem 19 is moved by a hand knob I5 mounted on the vehicle instrument panel or dash board 81, a connection such as a Bowden wire B8 passing through its casing or armor 98a operatively connecting the knob 85 to the valve stem 19. Thus by movement of knob 85 a pre-selection of either the high speed or low speed axle gear ratio may be effected. After the knob has been moved to the position corresponding to the desired gear ratio, release of the engine throttle controlor accelerator pedal to reduce the engine power to an extent sufficient to cause a torque reversal between the engine and the vehicle drive wheels will cause an automatic shift to the desired vgear ratio.

Y The novel clutch construction which permits this shift to take place without noise or ,iar and without imposing any excess strain on the drive largement Il of shaft 22 is provided with two rows of teeth 3| and 32, preferably ofthe same chordal thickness. Teeth Il are comparatively long, whileteeth 32 are short, so as to provide an annular space or groove 33 between the two rows of teeth.

Clutch collar 3l is mounted for axial sliding movement yon the top lands of teeth 3| and 32 and is provided with external groove 3l and internal teeth Il and 31.

As shown in Figures 3 and 4', teeth 3l are of comparatively short axial length, while teeth 31 are longer and also somewhat thinner. Teeth 31 are symmetrically aligned with teeth 36, so that thesides of teeth 33 project slightly either side of the corresponding sides of teeth 3l,V as seen in somewhat exaggerated form in diagrammatic views'lA, 3A and IA. Teeth 33 and 31 are thick and thin respectively so as to interlock with the shaftteeth 'and maintain the collar in the high or low ratio, as will hereinafter appear.

I ow ratio gear 23 is provided with a series of comparatively short clutch teeth 33, spaced fromA the helical teeth to provide a clearance groovev 33, for manufacturing purposes. Teeth 3B are f preferably so spaced as to provide a meshing fit with teeth 3l, with acomparativeiy small backvlash, but if desired the backlash may be lncreased within limits, provided that a proper reduction is made in the shifting force to avoid premature engagement, as will be hereinafter pointed out.

High ratio gear 21 is provided with a series of clutch teeth Il, which are'l spaced from the helical teeth to provide an annular groove I2. Teeth 4I (Figure 6) are somewhat thicker than teeth 33 of gear 23, so as to avoid excessive backlash when meshed with narrow teeth 3l of the collar. If desired, the backlash may be varied within limits, as will hereafter appear.

The clutch collar is accordingly mounted for axial sliding movement on the countershaft selective engagement with the'clutch teeth of the low speed gear or the high speed gear, and by providing collar teeth 38 and 31 and clutch teeth 33 and Il with end faces as indicated at 33a, 31a, 33a, and Ila, respectively, lying in surfaces of revolution lwhich are normal to the side or working faces of the clutch teeth and by properly selecting the area of said/end faces and the length of the teeth with relation to the backlash or clearances between the teeth and the disengaging and engaging forces applied to the clutch collar, I have discovered that the shift between ratios may be made by merely relieving the driving pressures or upon normal torque interruptions without disconnecting lthe prime mover from the mechanism, silently and without clash or shock to any of the parts of the mechanism. During the shift operation, after disengagement from one ratio the fiat tooth ends slide relatively in frictional engagement without burring or rattling until substantially complete synchronization of the speed of the collar and the engaged pinion is attained before meshing engagement can occur as hereinafter described in detail.

In order to insure this smooth sliding action of the contacting tooth ends before driving engagement of the gear c-lutch teeth with the corresponding clutch collar teeth, the tooth ends of the collar and of the clutch teeth of both gears 26 and 21 are accurately ground-so that the end surfaces of each row or ring of clutch 10 teeth lie as exactly as machine tolerances will permit in a surface of revolution generated about the axis of revolution of the corresponding clutch collar or gear, and the edge between the end surface andthe side and top surfaces of each tooth is square and sharp without any chamfer or burr. f

With tooth end faces so formed and smooth surfaced and with the cross sectional areas of the teeth of one set substantial-ly equal to the cross sectional area between the teeth of the ad-l The invention may be carried out by employing clutch teeth whose end faces are either normal to the axis of rotation or are inclined to provide a nesting or mating frusto-conical shape, so that when they are disposed in end-to-end rubbing, engagement during the synchronizing dwell, they will be maintained out of mesh, without manifesting any appreciable tendency to intermesh until the parts have been completely synchronized. Inclined tooth end forms are advantageous in gear mechanisms in which a centering action is desirable, as the frusto-conical ends set up a definite centering action, insuring proper concentric rotation during the synchro` nizing dwell. Tooth shapes of other forms may also be used, so long as the surfaces of the confronting tooth ends are generated by parallel lines (either straight or curved) rotated about spaced points onthe axis of the clutch members.

In Figures 3 and 4 and 4A, the parts are shown in low gear, with teeth 3G of the clutch collar engaged with teeth 38 of low speed gear 23. The torquing forces are indicated by the arrows, the downward force exerted by teeth 3| of the countershaft taking up the clearances and driving the collar. The torque is transmitted through collar teeth 36 to teeth 38 of the low speed gear, as indicated in Figure 4. Since the clearances between teeth 3i and 3l are taken up, and teeth 31 are narrower than teeth 36, in normal driving relationship, the latter may be said to be hooked over the ends of teeth 3|, so that, should the collar tend to shift to the right (Figures 3 and 4) the corners of teeth 3S will vabut the corners of teeth 3| and block such movement so long as power is being transmitted. When a reversal of power occurs, for example by momentarily releasing the accelerator and causing the vehicle to drive the engine, with the parts in the low ratio as seen in Figure 4, the clearances on the opposite sides of teeth 3i are taken up, and unless the clutch collar is forced to the right by a predetermined shifting pressure at this time, the opposite corners of teeth 33 will engage the opposite corners of teeth 3| and the teeth will again be interlocked. Movement of the clutch to the left is limited through engagement with the end of drive pinion 23.

From the'foregoing it is apparent that, when the axle is shifted into the low ratio, the clutch collar cannot be shifted out of engagement with the clutch teeth on the gear so long as power'is being transmitted in either direction between the countershaft and gear. When it is desired to shift the collar out of low sacra mined pressure sumcient to effect disengagement when the application of power to shaft 22 is momentarily interrupted, as for example by releasing the accelerator. As soon as the tooth pressure is relieved or decreases sulciently under such conditions, collar 34 slides to the right a slight distance and brings the corners of teeth 33 past the corresponding corners of countershaft In the event that power of only small magnitude is being transmitted when the shifting force is applied to the collar, the latter will promptly bring the corners of its teeth into engagement with the comers of teeth 3|.

Engagement of teeth 33 with teeth 3| under the conditions just described will momentarily arrest the collar, but if thereafter the transmitted torque drops to a value suiiicientiy low teeth 33 will be pulled past the corners of teeth 3|. By constantly urging the collar to the right during the disengaging action under the proper pressure, which is selected with relation to the tooth lengths, areas, backlash, oil viscosities and other practical factors, disengagement occurs before'a complete torque reversal can hook teeth 36 over the opposite corners of teeth 3|.

In Figures 6 and 6A the parts are illustrated in the position they assume in high gear, with collar teeth 31 meshed with clutch teeth 4| and gear 21. In this condition of the parts, collar teeth 36 are located in the space 33 between the rows of teeth on the countershaft, and do not transmit power, while teeth 32 transmit power to the collar through teeth 31, and the collar transmits power to clutch teeth 4| of the high speed gear, in the manner indicated by the arrows in Figure 6. Teeth 31 being narrower than teeth 36, the clearance is taken up by the driving forces and locates teeth 36 with their corners opposite the corners of teeth 3|. Accordingly, when the collar manifests a tendency to shift to the left, it is blocked by the corners of teeth 3|, in either direction of power transmission.

In high gear, the clutch collar abuts the end of gear 21. which limits its movement to the right. The inner edges of gears 23 and 23 terminate slightly short of the sides of spur gears 23 and 21, so as to avoid contact with clutch collar 34.

The shift out of high gear is effected in a manner similar to that just described with respect to low gear, by applying a disengaging force of predetermined magnitude to the collar and urging it to the left until release of the accelerator reduces the tooth pressure to a value suiliciently low to permit the shift to take placel In Figures 5 and 5A the clutch collar is illustrated in the position it assumes when it has been shifted out of low gear and is undergoing a synchronizing dwell prior to shifting into the high ratio. Since the flat ends 31a of teeth 31 are disposed in frictional rubbing engagement with the ilat ends 4|a of teeth 4| and teeth 31 and 4| are not meshed, when the engaging pressure on the collar is properly proportioned to the area to teeth 36 applies torque to teeth 33 in the direction indicated by the arrow 36', the baklh 12 between the teeth being exaggerated and designated by reference vcharacter 33'. In the low gear position illustrated in Figure 4A, teeth 33 are in effect hooked over teeth 3|, and because of the'diiference in chordal thickness of teeth 33 and 31 a relatively large degree of backlash 31 is present between teeth 3| and 31. The corner designated 33h of tooth 3B engages corner 3Ia of teeth 3|, so that the latter constitutes an abutment which effectively restrains the parts against shifting out of low gear so long as any appreciable driving torque is being transmitted. When a coasting torque is being transmitted,

tooth 3B will interlock with the lower of the twoI teeth 3| illustrated in a manner similar to that, Just described.

f. In Figure 5A the parts are in the dwell or neutral position, with thick teeth 33 meshed with teeth 3| of the countershaft, and thin teeth 31 are disposed in sliding engagement with end faces 41a of high gear clutch teeth 4 I.

In Figure 6A the parts are shown in high gear, with the driving torque being transmitted from teeth 32 to teeth 31 in the direction indicated by the arrow 32', and from teeth 31 to teeth 4| in the direction indicated by the arrow 31', the backlash present between the teeth being designated 4|'. In this instance the collar is locked against shifting out of high gear by reason of the corner 38e of tooth 33 abutting or locking.

behind corner 3 Ib of toothli.

I'he novel clutch and gear assembly just discussed is accordingly automatically locked when shifted into either gear ratio and transmitting power, and yet may be readily shifted from one ratio to the other without burring, rattling or clashing of the teeth by momentarily interrupting the application of power to the driving shaft when disengaging and engaging pressures of properly selected magnitude are applied as above set forth.

It will be understood that because of the variable interdependent factors which enter into practical workable designs of my invention which are generally dependent on the sizes and capacities of the parts, mechanical ease of shifting of the particular mechanical 'parts employed, lubricant viscositles and other factors, designers utilizing my invention will have a substantial range of practical choice, as will be hereinafter pointed out in detail.

The mechanism also embodies means for preventing any minor shifting of the clutch collar into contact with the shifting yoke, for instance when reversals of torque occur during normal operation, thereby avoiding wear ofthe parts. To this end, three bores 43, preferably located |20 degrees apart, are provided in countershaft enlargement 22. Located in each bore 43 is a compression spring 44 acting upon a ball detent 45. Three of the full length collar teeth 31 are cut away to provide bevelled faces 31h, and three corresponding collar teeth 33 are cut away to provide bevelled faces 38h, for cooperation with detents 43. Faces 36h and 31h are preferably disposed at an angle of approximately 30 degrees with the countershaft, so that the ball detents exert a strong holding action upon the collar ir, either o'f its shifted positions. minor shifting movement of the clutch collar can occur, and it is likewise further restrained against unintentional shifting movement when power reversals occur. Since bevelled teeth 36h and 31h are only three in number and their ends lie in the same plane as teeth 36 and 31, they do not Accordingly, no

, interfere with the proper sliding action vand block- With the engine driving the vehicle, and with the axle in the low speed driving ratio, as shown in Figures 3, l4, 7 and 8. The axle may be shifted into the higher ratio by merely pulling out knob II, so as to place casing 5B into conununication with the intake manifold, and manipulating the engine accelerator, it being unnecessary to disengage the clutch. j

With knob 86 pulled out, the manifold suction causes an operating pressure on diaphragm 62 tending to move toward the high speed driving position with a predetermined relatively high disengaging pressure against the action of spring 61. However, so long as power is being transmitted through the gearing, no movement of shift collar occurs because tooth pressures set up a frictlonal force and the teeth are interlocked res istlng the pull of the diaphragm. Accordingly, the mechanism is preselected for high gear operation, but the actual shift is held in abeyance until delivery 'of lpower is interrupted or a torque reversal occurs in the axle.

With high speed preselected as just described, the shift is carried out by momentarily releasing the vehicle accelerator or otherwise interrupting the delivery of power to the axle. This reduces the tooth pressure and releases the interlock perss,ois i,

mitting clutch collar Il to be shifted at the time stant speed, through the momentum of the vehicle. Because of the difference in gear sizes, high speed gear 21 is rotated at a lower speed than low speed gear 26, and since shaft 22 at the moment of pull out of the collar from the low speed gear is rotating synchronously therewith, shaft 22 and collar 34 in the condition shown in Figure 5, must be decelerated to synchronize them with the speed of teeth 4i. y

The engine and the associated parts, however', rapidly decelerate shaft 22 and collar 34 substantially to the speed of gear 21, at which time the predetermined pressure exerted by diaphragm 62 on the collar causes full meshing engagement with the clutch teeth of high speed gear 21, as seen l'in Figure 6, silently and without shock.

Accordingly, the axle is shifted quickly. silently l and without burrlng, clash orvjerk 'from the low speed to the high speed ratio without need of disengaging the vehicle clutch. 'I'he entire shift operation requires but a few seconds to complete in practice, and is effected in substantially the same way whether the vehicle vis on the level, or travelling up or down grade at the time of the shift operation. When the vehicle is travelling down grade the shift period may be shortened slightly due to acceleration of the vehicle while coasting during the shift operation, but since llneshing occurs automatically upon synchronilation, slight variations in the time of shift are immaterial. Upon conclusion ofthe shift theV 14 accelerator is depressed to cause the enginev to drive through the high speed ratio.

The driver may ascertain when the shift hasy been completed by observing the tendency of the vehicle to drive the engine, or by observing the speedometer. If he should happen to accelerate the engine before the shift is completed, it is ini-- possible to damage the .mechanism'because the ends of the clutch collar teeth 31 will merely slide smoothly on faces l4i a of the high speed clutch teeth until the engine is again decelerated until synchronization of the clutch teeth occurs. x The shift from high gear into low gear is made in a manner similar to the shift into -high gear, except that after pre-selection the shift is not completed until after the engine has been decelerated and then accelerated. To effect this shift, with the vehicle operating in a high speed ratio.- knob 86 is pushed in to open chamber 59 to the atmosphere. This frees spring 61 to urge arm 64. toward the low speed position with its maximum force. However, so long as power is transmitted through the axle. the frictional tooth pressures and interlock of the teeth prevents theclutch` collar from shifting, with the result that the axle is maintained in the high speed driving ratio after pre-selection by so operating the knob. With low speed pre-selected as just described, the ac- .celerator is momentarily released or the power f 3.6 .into rubbing engagement with end faces 38a of teeth 38 with a lowered pressure due to partial extension of the spring.

Under the conditions just described, gear 26 is rotated through momentum of the vehicle at a greater speed than gear 21 and shaft 22, and ac-- cordingly the engine must be accelerated, rather than decelerated, to bring the clutch collar into synchronism with teeth 3B. During acceleration of the engine, the collar teeth smoothly and silently ride upon teeth 38, and permit intermeshing only when the speeds are substantially synchronized. Upon substantial synchronization of the collar and gear 26, spring 61 promptly shifts the clutch collar into the position shown in Figure 4, meshing teeth 3.6 with teeth 38 and completing the shift into low gear.

vI have found that when shifting from thehi'gh .to the low ratio, the rotational inertia of the engine ywheel, propeller shaft and associated parts is a real advantage, because it prevents the engine from being accelerated too rapidly and possibly passing the point of synchronism too quickly to permit meshing of the teeth. In practice, with' properly proportioned parts, it has been impossiblel to accelerate the engine with sumcient rapidity to produce a clash or shock in shifting from the high to the low ratio. g

The axle may also be readily shifted when theI vehicle is at a standstill and the engine is running, by pulling out or pushing in knob I6. Should the clutch teeth not be aligned with the -teeth of the selected gear when pre-selection is made, the parts will immediately go into the mesh when the vehicle clutch is engaged, so as to ro tate shaft 22. This operation also occurs without shock because shaft 22 can only rotate a distance less than the chordal thickness of one of the clutch teeth'before engagement occurs, thereby preventing relative rotative speeds of any appreciable 'magnitude from developing before meshing can occur.

Proper-tions and essential specific structure As hereinbefore pointed out generally. it is essential to the proper functioning oi my improved shift mechanism, that a proper relationship be established between the shape and area of ends .of the intermeshing teeth, the backlash and the length of the teeth with respect to the engaging and disengaging pressures. The tooth interlock disclosed while permitting desirable selection of the desired ratio well in advance of the actual shift, or so-called pre-selection, is not essential to the operation.

An important requirement is that each cooperating set of engagingfend faces of the collar teeth and the cooperating clutch teeth be smooth and lie in parallel surfaces of vrevolution generated by a pair of lines rotated about spaced points on the axis of rotation of the clutch collar, and that their corners be sharp and free from rounded or chamfered edges. The areas ci' the engaging end faces of the teeth and the backlash must be so chosen `with relation to the engaging pressures that the time interval required for the tooth of one member to pass over the space between two teeth oiy the other member is too small to give the tooth an opportunity to drop into space until the teeth are substantially synchronized and so that the parts will be brought into substantial synchronism in a comparatively short interval of time without burrthe interlock is used, relatively higher disengaglil ing or clashing. Since these factors may be varied to meet individual design preferences, it will be apparent to those skilled in the art that various operative practical combinations thereof are available. I have also found that best results v&.1'""secured when the widths of the engaging teeth clutch teeth is obtained, but should not be so great as to cause burring clash or premature engagement of the clutch teeth. It is also necessary to apply suilicient disengaging power to assure quick disengagement of the clutch teeth when the driving pressures are released after preselection of a new driving ratio. The proper engaging and disengaging pressures will be dependent not only on the tooth areas, shapes, lengths and backlash, but will be affected by resistance to relative sliding of the parts caused by oil viscosiies. mechanical ilts and the like. While the limits of proper operating pressures in practical transmission assemblies are not narrow for any given construction these limits are definite and predetermined by the factors above set forth. And within limits, the greater the backlash between the meshed teeth, the lower the engaging pressures must be, to avoid meshing before synchronism with resultant shock and jerk.

The use of interlocking teeth, as above pointed out, is desirable because it permits effective preselection of a changed speed ratio well in advance oi' the actual shift, because even though disengaging pressures are applied as soon as the preselection is made, so long as driving power is applied. disengagement of the clutch teeth will not occur due to the interlock. To assure disening pressures should be applied than when the inter-lock or an equivalent device is not used. When the interlock or the like is not used unless an arrangement, as for example a clutch pedal operated valve control of the well known Columbia axle type, is used to apply the shifting pressures at the time the shift is desired, the disengaging pressure must-be lowered sufficiently to avoid forcing the teeth out of mesl'ibefore the driving pressures on the teeth are released.

By way of a specific practical application of my invention the axle and controls therefor so far described were designed for and have been and are being used successfully in trucks having engines Aof from 318 to 382 cubic inch displacement with I' and is provided with nine teeth.

Low speed helical pinion 2 5 has a maximum outside diameter of 4.863 inches and has fourteen teeth, 3% inches long. It is journalled on a portion of shaft 2-2 approximately 2.62 inches in diameter. Clutch teeth 3l are thirty-two in number, are il, inch long and have an outside diameter of 4.103 inches. Teeth 38 also have a pitch diameter of 4 inches, a chordal thickness 'of 0.195 inch and a chordal spacing of 0.197 inch.

Helical high speed pinion 21 has a maximum outside diameter of 5.776 inches and has seventeen teeth, three inches long. on a portion of shaft 22 approximately 2.96 inches in diameter. Clutch teeth Il are the same as teeth 33, except that they have a chordal thickness of .207 inch and a chordal spacing of 0.185 inch. Both sets of clutch teeth have a pitch of 8,V a pressure angle of 25 degrees and a full depth of .198 inch.

Clutch collar 34 has an outside diameter of 51/2 inches, a width of 1%.inches, and a minimum internal diameter of 3.79 inches. Teeth 35 and 31 are thirty-two in number vand have `a pitch diameter of V4 inches and a depth of 4.125 inches. Teeth 38 are 1%2 inch long and have a chordal thickness of .195 inch and are chordallyv spaced .197 inch so that they may mesh with teeth 38 with a backlash of approximately .002 inch. Teeth 31 are spaced g inch from teeth 36, are 3%4 inch long and have a. chordal thickness of from .155 to .165 inch so that they may mesh with teeth Il with a'. backlash of from .020 to .030' inch. The sides oi' teeth 3B project from 15 to 20 thousandths of an inch either side of the corresponding sides of teeth 31.

The weight of the collar has a bearing upon the shifting characteristics of the mechanism because, as the teeth of the collar slide against the high or low speed clutch teeth,l whether or not -the collar will respond to a tendency to mesh with stood that by decreasing the backlash and/ or theA It is journalled engaging pressure the collar weight may be re- Y duced.

The shaft teeth have a maximum outside diameter of 4,147 inches and a chordal thickness of .195 inch, a pitch of eight, a full depth of .198 inch and the two rows are spaced lf2 inch apart. The teeth are chordally spaced 0.197 inch, so as to mesh with collar teeth 36 with a backlash of .002 inch and with teeth II with a backlash of from .022 to .032inch. Teeth Il are 11; inch long and teeth I! are il, inch long.

Shift arm Il is approximately two inches long, andthe effective area of diaphragm l2 is such that with the vacuum applied, and high gear selected, a pull of from approximately 125 to 175 pounds is exerted on clutch collar u, tending to pull it out of mesh with the low speed teeth.

approximately 125 to 175 pounds upon the clutch collar.l After` the clutch vhas been shifted out of high gear, and duringthe synchronizing dwell,

with tooth end facesla and Ila-in sliding en'.

gagement, spring Il -exertsa force of from .30 to pounds upon the clutch collar, tending to shift it into the low ratio. Y In short, the spring strength and vacuum diaphragm or piston areas are preferablyy so selected that the disengaging or pullout" force bears a ratio of from 2 to 1, tov4 to 1 with respect to the engaging or pull-in" Aforce for best results with the other parts proportioned as disclosed. l

Teeth 36 and l0 are of sumciently great chordal thickness to establish a backlash of approximately .002 of an inch, while the backlash between teeth 31 and 4| is from .020 to .030 of an inch. The backlash on the low side may, however, be increased by decreasing theengaging pressure, and on the high side it may be decreased by increasing the engaging pressures.

It will therefore be understood that my invention is not limited to use of any particular degrees of backlash or to any of the other proportions and arrangements disclosed by way of specic example, as various ranges, proportions and arrangements of parts may be employed in combination with shifting forces of the proper magnitudes to secure the benefits of my invention.

Modified control mechanisms While I have shown diaphragm 82 actuated toward the low speed side with a spring, and toward the high speed side in response to engine intake vacuum, thereby providing a simple arrangement giving relatively high disengagingV ly connected to a rod 8| carrying a piston assembly 02 working in a cylinder 93, which is closed at both ends. Compression spring 94 acts upon the piston assembly so as to urge theparts toward the low speed driving range, but it is to be understood. if it is not desired to take advantage of an automatic shift into the low ratio when the vacuum fails, spring 04 may be omitted.

The opposite ends of cylinder 8l are placed in communication, by means of a pair of conduits Il and 98, with a control valve 91 of modifled construction. Valve rod 98 is controlled' by wire I0 in the same manner as valve rod 18, but carries valve member 99 which is hollow and has a wide annular groove |0| constantly in communication with a port |02 leading to conduit 1I connected to the intake manifold.

Groove |0| may be selectively aligned with a port |03 communicating with conduit 8l or with a port |05 communicating with conduit". In the position shown in Figure 12, the intake manifold is in communication with the upper end of the cylinder through port |02, groove IUI, and port |03. The lower end of the cylinder is' in communication with theatmosphere through conduit 0l, port |05 anda-plurality of Aexhaust ports |00 provided in the valve casing.

Whenvalve member 99 is shiftedinto its righthand position, groove |0| placesthe lower part of the cylinder in communication with the intake manifold throughport |05,'-groove |0| and port |02. Under these conditions the upper part of the cylinder is placed in communication with the atmosphere through conduit 05, port |03, the

hollow interior |01 of the valve, ports |08 in the end of the valve, and ports |08 in the valve casing.

Accordingly, by shifting knob 88 in or out, vso as to place either the upper or the lower end of the cylinder in communication with the intake manifold, the axle may be shifted into the low or the high ratio respectively. in the manner as previously described.

Speedometercontrols When the drive axle gear ratio is changed it is obvious that the gear ratio of the speedometer drive must be changed accordingly if correct speedometer readings are to be maintained.

While the prior speedometer shift mechanisms in common use may be used with my improved axle, in such prior mechanisms the speedometer shift occurs at the-time of selection of a ratio, and thereafter, until the actual shift is effected, the* speedometer reading is erroneous.

In Figures 7, 8 and 9 I have illustrated a novel speedometer drive-control mechanism which will automatically shift a speedometer change speed gearing only at the time of the axle shift to establish the proper driving relationship between the drive shaft and the speedometer in both the high land low shifted positions of the axle.

In Figure 7 a conventional clutch housing and a selective shift transmission i2, having a gear shift lever v| I3, are shown connected to engine 10 in well-known manner, and the output shaft of the transmission drives a propeller shaft I4 through a universal joint assembly I0. Shaft Il is coupled to shaft I1 in well known manner. Driven from the transmission tail shaft in well known manner is a speedometer drive shaft III (Figure 9). Shaft IIB is connected to a speedometer change speed transmission il of any sultable character embodying selectively shiftable i9 two speed gearing having speed ratios corresponding to the speed ratios of the gears in the axle, so that when the axleand speedometer drive gear are operating in the low ratio or when the axle and the speedometer drive gear are in the high ratio, the speedometer will correctly indicate the vehicle speeds.

The change speed gear is controlled by a shaft ||8 carrying a. shift arm H9. With the arm in the position shown in Figures 'l and 9 the speedometer drive gear is in the low ratio. A flexible drive shaft assembly I|2| leads from the output side of the change speed gear ||1.to a speedometer |22 mounted on the vehicle dash, in well known manner.

Shift arm I I9 is controlled substantially directly in accord-ance with the movements of axle.

shaft lever 54 to change the speedometer gear ratio only when the axle is shifted into the selected ratio. A lever |24 mounted on shaft 49 is connected to a Bowden wire control assembly, comprising an actuatingwire |25, and a vsheath |20. The forward end of sheath |26 is connected to a bracket |21 carried by casing H1, and wire |25 passes4 through an opening in the end of lever` ||9 and is provided with a pair of spaced abutments |29 and |29. Interposed between the abutments and arm ||9 are a.y pair of compression springs |3| and |82, preferably of equal free length and strength. In the position shown in Figure 9, spring |3| isl compressed between abutment |28 and the arm, holding the latter in the low speed driving position.

In operation, when clutch collar 34 -is pulled into the synchronizing position shown in Figure 5, lever |24 is simultaneously shifted into a position intermediate the high and low speed positions, and through wire |25 moves speedometer shift lever ||9 into an intermediate position and interrupts the drive to the speedometer. When the collar moves into full meshing engagement with the clutch teeth of high speed gear 21 as 'shown' in Figure 6, arm |24 through wire |25 simultaneously shifts speedometer gear shift lever ||9 into the high speed driving ratio. If, however, at the moment of shift the speedometer drive change gears have their teeth disposed in end-toend abutting relationship, spring |32 will yield and subsequently bring the parts into proper driving engagement, thereby avoiding blocking the shift of axle shift lever 54.

The speedometer driving gear mechanism will then remain connected in the high speed ratio, until the axle is shifted out of the high speed ratio, at'which time arm |24 will actuate wire |25 to first disconnect the speedometer drive, and then, as the axle is shifted into the low speed ratio, the speedometer driving gearing will'be shifted into the corresponding speedometer low speed driving ratio.

It will accordingly be seen that the speedometer will be disconnected while clutch collar 34 is dwelling between high and low speed positions, and will-correctly indicate the vehicle speed at all other times, including the periods of pre-selection. f

In Figure 13 I have disclosed a modified form of speedometer control embodying vacuum responsive operating means to replace the mechanical connection to the axle shift lever as disclosed in Figures 6 to 9.

Cin this form of the invention a T connection |35 is inserted in vacuum line 88, and connected thereto, by a conduit |36, is a vacuum chamber assembly |31 having a diaphragm |39. Connect- 20: ed to diaphragm |38, by means of a rod |33 and a clevis |4|. is -a modified control lever |42 secured to shaft I|8 of speedometer speed change control mechanism ||1.v A compression spring |43 constantly urges the diaphragm and rod |39 toward the low speed speedometer drive position.

In the operation of this arrangement when knob 86 is pulled out to place condut 68 in communication with the intake manifold, diaphragm |38 is moved to the right against the action of the spring |43 and shifts the speedometer into the high speed driving ratio. When knob 86 is pushed in., or if the vacuum should fail, diaphragm |39 will move to the left under the iniiuence of spring |43 shifting the speedometer gearing into the low speed ratio.

Since, in the preferred embodiments of my invention, shift into either speed ratio occurs only after release of the driving pressures,'during the period of pre-selection, this form of speedometer control will cause an erroneous speedometer reading until the actual shift is effected.

In Figures 14-20, I have shown a modification of my invention having radial as `well as axial teeth formed according tothe invention embodied in a planetary two speed axle -of substantially the same design as the subject matter to/which A. Ai Wiedm-aier Patent No. 1,815,689, granted July 21, 1931, is directed.

Shown, particularly in Figure 14, is an axle housing comprising a center section, generally indicated at |50, having an annularly shaped portion |52 and an annularly shaped portion |54, preferably provided with an integral bearing supporty member |56, said two annularly shaped portions being secured together in any conventionall manner as by cap screws |58.

Forwardly the center section is provided l with a circular opening '|60 `in which is supported pinion bearing cage |62 seatingy twin roller bearings |64`in which pinion shaft |66 is rotatably mounted.

Secured 'to and extending axially from annular portion |52 is tubular member |10. Oppositely extending tubular portion |12 is secured to and extends from annular portion |54. Bearing support member |56 of annular portion |511 and tubular end portion |10 are provided with roller fbearings |15 and |11 in which is rotatably supported the transmission-mechanism to be Adescribed.

The pinion shaft |66which is coupled at its forward end to the vehicle propeller shaft (not shown), extends rearwardly, terminating within the center portion of the axle housing in a bevel pinion |00. The bevel pinionmeshes with a bevel ring gear |82 which with generally cupshaped portions |65 and4 |81 constitutes a planetary gear housing,A generally indicated at |09. The housing |68 is rotatably supported at one end by an axially extending tubular portion integral with bevel ring gear |82 in roller bearing |11 and at its opposite end by an axially extending tubular portion |92 rotatably supported in roller bearing |15:

The cup shaped portion |81 of planet housing |98 'has a` wall portion |95 substantially transversely disposed with respect to its rotational axis and is provided with a correspondingv transversely disposed portion |91 axially inwardly spaced from said wall portion. Wall'portion and the axially inwardly transversely disposed portion |91 are connected by a desired number of planet pinion pins, one of which is` indicated at |90. 0n the planet pinion pins,

' 2l which are substantially equally radially spaced andparallel to the rotational axis of the planet housing. are iournalled planet pinions. as indicated at 2li.

The planet pinions :Il mesh with an internally toothed ring gear 202 which is carried by a generally frustro-conicai shaped member Ill s'ecured to the spider of the conventional dii'- ferential D comprising spider 2li. differential pinions 2li and differential side gears 2li.v Side gears 2|! are integral with axle shafts 2li and 2 I2.

l The teeth of planet pinions 20| mesh inwardly with the teeth of sun gear 2li. integral with an axially extending quill lll through which axle shaft 2|! extends and, on which a toothed collar' annular section I of the axle housing. 'Brake 22| is formed with internal teeth 22| adapted to mesh with teeth 224m collar 22| as illustrated in Figure 14. Y

In one position of the toothed collar 22|. power transmitted through the pinion shaft l, bevell pinion. |80. and bevel ring gear Ill. to the planet housing ill, will rotate the -planet pinions 2li bodily with the planet housing holding the planet pinionsagainst rotation on their pins. thus locking the internal ring gear. planet pinion. planet housing. and planet sun gear as a unit, so that the power is transmitted directly tothe axle shafts 2H and 2I2 through the diferential.- In the ,alternate selective position collar 220 connects the sun gear to the axle housing whereby the bevel gear setv and planet housing will drive the planet pinions about the sungear thus driving the planet ring gear and consequently the axle shafts at a greater speed than that of the planet housing.

Collar 22! at its inner end is provided with a plurality of inwardlydirected radial teeth 222 which. upon movement to the. left. may engage the axially directed teeth 220. and outwardly directed radial teeth 22e which may. upon movement tothe position illustrated in Figure 14. engage the inwardly directed radial teeth 22| on the stationary brake member secured to the housing, Collar 22! -is also provided with an external annular groove 2 into which radially directed trunnions 262 project to shift the collar axially on mating internal splines 2li in the collar and external splines l on the quill 2H. The weight of' collar 220 has a direct effect upon the shifting characteristics of the mechanism and the tendency of the teeth on the collar to disengage from and to intermesh with their mating teeth. Synchronism depends to some extent upon the inertia ofthe collar. I have found that a collar weighing .approximately ounces in a mechanism ofthe sise hereinafter disclosed is satisfactory. A

In this shift mechanism. as in the hereinbe- A fore described double reduction two-speed shift .liol inside diameter of 3".

ascia length of the contact surface between the teeth when they are intermeshed.

It is essential that the 'cooperating end faces of the collar teeth and the teeth adapted to mesh s therewith. which abut before engagement and intermeshing. be smooth and lie' in parallel 'surfaces of revolution generated by a pair of lines rotated about points on the axis of rotation of the collar. and that all of the faces have sharp corners free from rounded or chamfered edges. The area of the end faces of the teeth and the backlash must be correlated tothe pressures tending .to engage the teeth after abutment in order that the teethl will properly engage and l5 tend to intermesh before that time thus burring or chipping the sharp edges. These factors may be varied to m'eetvarious conditions and circumstances.

The pressure to engage and mesh the teeth should be yieldingly and lightly but positively applied and sufficient to complete the intermeshing upon the substantial synchronism between the mating teeth. It has been found that the disengaging power should be of suilicient magnitude. which is substantially greater than that of the engaging power, to assure swift disengagement after preselection and torque interruption to avoid the possibility of the collar teeth so being caught upon torque reversal thus interrupting the shift sequence.

In the -practical application of my invention to a planetary two-speed overdrive axle for a medium size passenger car. I have found the following relationships to provide a very satisfactory mechanism.

The overall gear ratio in this unit between pinion shaft Il. and axle shafts 2li and 2i2 is 4.11 toti in direct ratio and 3.65 to 1in overdrive ra io.

The 8 equally spaced axially directed housing teeth 22| have the following approximate dimensicns: outside diameter of 2"; length of V4". The d inwardly directed. mating radial teeth 222 have a root diameter of 2": an inside diameter of 13; alength of V4".

The 12 equally spaced inwardly directed, stationary radial teeth 228 havey the following approximate dimensions: lRoot diameter of St/4":

The 12 outwardly directed. mating radial teeth 22| have an outside \diameter of 3%"g an inside diameter of 3": a

length oi Ys".- 1

The relationship of the chordal width of the 55 mating teeth is as near equal as practicable. 'being varied only to the extent necessary to maintain a backlash of approximately .015" to .025" therebetween.

l-Clollar 22| may be shifted by any suitable 69 means. -Shown in Figure i4 is lever 2" 4,lournailed for rocking movement on fixed member 2l2 which is securely attached to the annular portion Ill in anyconventional manner. The upper arm of lever 2li is provided at its end 05 with s substantially spherical portion :u for optional contact with the sides 2li and 25| of the lateral slot 2li-'in piston rod 21|. The lower lever arm is bifurcated providing a yoke 2li into which are secured a pair of trunnions 242 dis- 70 posed in groove 2 of the collar.

In order that the sun gear 2li may have sufflcient freedom 'of self centering movement rela tive to the planet gears to equalize the tooth pressures between the sun gear and the various planet gears. it is desirable that the quill lil mesh upon substantial synchronism but will not saule have a limited amount of radial iloating move'- mentirelative to the axle shalt 2|2. However. as too great a freedom of floating movement would interfere with the centering of the collar K teeth 222 and 224 relative tothe mating teeth 220 and 220, means are provided to limit the radial Vfloating movement of the quill. This,

means may conveniently comprise a bushing 200 disposed between the quill and the axle shaft to prevent forces. such as the weight oi' the collar,

n' acting on the quill, fromicausing misalignment oi the clutch teeth. A bushing having an internal diameter approximately 0.005" greater than the external diameter of the axle shaft and an external diameter approximately the same as the internal diameter of the quill has been found' satisfactory for this purpose.

In Figuren I have shown a vacuum motor, generally indicated as 210, comprising a cylinder 21|, conduit nipples 212 and 210, piston 211, and piston rod 215, secured to the tubular portion |12 in any conventional manner. Condults 212 and 212 are provided to optionally apply intake vacuum of the vehicletengine to the desired side oi' the piston 211 in order that the piston may exert thrust on the piston rod 215 to which it is attached, in the disired direction.

The eil'ective area of piston 211 is such that the vacuum normally exerts a pull of approxi-l mately 80 pounds pressure on the piston rod 210 which in turn transmits this pressure to the substantially spherical end 254 on lever 250.

to disengage the teeth 222 and 220 or 224 and 19) into which are inserted coil springs 204 and In l view oithe fact that the leverage ratio of the lshift lever is approximately 3% to l, a pressure -of approximately 250 pounds is initially exerted 200 respectively. The outer end of the bore 200 is tapped to accommodate closure cap screw y200. The size of the c'oil springs is determined by the magnitude of pressure necessary to intermesh the mating teeth.

As will be more fully explained, the reciprocable piston merely disengages one set of the teeth and moves the other set of mating teeth to a point short of sliding engsgementrcoil spring l204 or 200 functioning as the only/power means eilective to mesh the mating teeth.

In one direction of travel contact of the piston 211 with annular member 210 on cylinder member 21| limits the length of travel of the piston rod'215, while in the opposite direction of travel the engagement of the outer end of piston rod 215 with the end of the'vacuum cylinder 21| .f y limits the length of travel of the piston rod.

` j (ioil springs 204 or 200 exerting a pressure oi' fapproximately 35 pounds have been found satis- 'iactory to intermesh the mating teeth after subjstantial synchronism without clashing or raking of the teeth before intermeshing.

Any one of the many known types of valve construction may be employed to optionally connect 17;" vacuum cylinder conduits 20| or 202 to the eny vacuum. In Figure l2 is shown one form g of valvecomprising a'three-way valve housing 01,

Operation The operation of the shift mechanism will now be explained. As shown in Figure 14 the device is in' overdrive or hish ratio, the sun gear 2li being lockedv to the stationary member 205 through the external splines 241 on the quill 2|1 and the mating intennal splines 24| in the collar 2,20, the external teeth 224 on the collar and the internal teeth 2210 on the stationary member.

To shift to low or direct ratio the vacuum piston 211 is caused to move to the right from the position illustrated by the action of the engine vacuum through nipple 210 by control valve such as shown in Figure 10.

The initial movement of the pistonrod 215 compresses coil spring-204. The compression of the spring `causes the face 255 'of the lateral slot 250 to contact the spherical end 204 at the end of the shift lever 250. Continued movement ofthe piston rod to the right moves the yoke 250 to the left. The trunnion 242 in turn moves the clutch collar 220 to the left and causes teeth 224 to disensage from teeth 220. The disengagement is extremely rapid as the piston 211 is operating at its greatest power produced by the high engine v acuum. Swift disengagement is essen-v tial as the teeth must disengase before torque reversal interferes with the shift sequence. Movement of the rod continues until the outer end of rod 215 abuts the end of the cylinder 21|. The movement o! the rod is of such a predetermined distance as to move the ilat faced, sharp edged teeth 222 only approximately into abutting engagement with the mating, ilat surfaced, sharp edged teeth228 of the planet housing. Upon and not until, substantial synchronism of the collar and the planet housing does the pressure exerted by the still substantially fully compressed spring 204, which has caused teeth 222 to contact teeth 220, force the teeth 222' of the collar into intermeshing engagement with the teeth 220 of the planet housing.

When the colla-r 220 is disengaged from the stationary teeth 220 the planet sun gear 2|0 becomes a i'ree member, its rotation being controlled by the direction and speed of rotation of the planet ring gear 202 and planet housing |00. Assuming the collar 220 to be disengaged from both its mating sets of teeth 220' and 220, the planet ring gear speed and direction is controlled by the speed and direction of the vehicle wheels (not shown) to which it iscoupled by the axle shafts2|| and 2|2, differential D and frustroconical shaped member 204.

The forward motion of the vehicle in normal operation rotates its wheels in a clockwise direction. This in turn rotatesvthe planet ring gear 202 to which the wheels are coupled in a clockwise direction.

The speed of rotation of the planet`housing A tive speed oi' rotation and direction of travel of the planet housing |00 and planet ring gear 202.

Upon deceleration of the engine for torque interruption'and disengagement of the teeth the hecomesless than the ring gear tends to on their pins l|| the chaine is accelerated planet housing equals the speed of the planet ring gear the planet pinions are not rotating on` axis ami consequently the sun gear rotates at a speedfequai to'that ofl the planet housing. that is. the lplanet housing speed and the planet sun gear-'speed are synplanet"housing decelerates.' when power is being transmitted in eith'er direction the larger end portions oi' teeth 22|' will, however, pass between the larger portions of teeth 222' so that, upon cessation or interruption of power transmission through the intermeshed teeth. teeth 222' may bedrawn away from teeth 22|' to discontinue the drive therethrough. The

teeth of these two sets may also be readily encased in the manner described above in connection with Figures 14 to 1'1, inclusive.

Teeth 22,4', corresponding to teeth 224 of Figure 18, and 22|', corresponding to 22| of Figure chroniled, at Which time the Ueeth`-2l2 ad Il.

intermesh by the action of the stili compressed springs 2|| and the planet housing, pinion, sun gear and ring gear are interlocked and rotate as a unit.

Conversely. inA shifting from tio to overdrive the teeth 222 and 22| are disengaged and the engine is decelerated while the speed of the planet ring gear 2|2, to which the vehicle wheels are coupled,` stantially the same. With the engine decelerathousing i|| decelerating, the riiig gear 2|2 tendsl torotate the :anions 2|| on their pins in a 'clockwise direction. This clockwise rotation of 'the planet pinions tends to rotate .the sun gear 2i| in a counter-clockwise direction.` The effect of this tendency to reverse the rotation of' the planet sun gear is to reduce the speedl of rotation of the planet sun gear to zero, at which time the clutch teeth-22| engage with the clutch teeth 22| by theaction of the compressed spring When the parts are in this position, as shown in Figure 14, and the vehicle is in forward motion, for example. the clockwise vrotation oi' the bevel pinion I|| rotates the bevel ring gear I|2 ina counter-clockwlse direction. Planet pinionsA slight osets or shoulders which overlap to maintain intermeshed teeth against disengagement during the transmission of power in rection.

In the arrangement illustrated the teeth 22|'. corresponding to the teeth 22|,of Figure 14, are provided intermediate the ,length of each side face with a lateral shoulder as indicatedat 22| making the teeth somewhat y'i' shaped in plan. The lateral extent of each' shoulder, however, is only a few thousandths'of an inch. Teeth 222', eo

either dicorresponding lateral shoulders, as indicated at 22|. The shoulders 22| and 22| are so located .along the length of the teeth that when the direct er bw n tends to remain subrresponding to teeth 222 of Figuren. are. provided along their side or working faces with.

- ing, and consequently the speed of the planet.

14. are Yalso provided lwith lateral oilsets or i shoulders as indicated at 22| and 222, respectively, which cooperate in the same manner as shoulders 22| `and 32| onteeth 22| and 22 to maintain teeth 22|' and 22|' in engagement during transmission of power therethrough. These teeth may also be engaged and disengaged under conditions of relative synchronization in the manner hereinabove described. v

In either event the shift into the selected gear is carried outquickly and without clash or jerk. insuring a minimum of loss of vehicle headway during the shift.

From the foregoing disclosure of the invention it is apparent that I have 'provided a novel multiple speed power transmitting mechanism which is of extremely simple design, enables the shift into low or high gear ratio to be carried out in a minimum of time under any and all vehicle speed and load conditions. silently and without clash or Jerk, and without disengaging the vehicle clutch, and 'it also embodies novel control means which make it possible to premanipulating the vehicle accelerator, and which `also shifts into one ratio if the engine should stall.

It is also to be understood that the'invention is not limited to coupling two rotating parts, but

may be advantageously employed in planetary or other type transmissions for coupling any twoy relatively rotatable parts wherein a rotatable part is selectively coupled to a stationary member to eiiect a speed change. and the recitation 'of relatively rotatable parts in the appended claims is intended to embrace the invention when it is embodied in those forms.

The invention may be embodied in other specific formsA without departing from the spirit or essential characteristics thereof. vThe' present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency'of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by ,United States Letters Patent is:

1. In a multiple power transmitting assembly,

` are coupled together: axial clutch teeth on each teeth 212' are hill! meshed with teeth 22|.`

shoulders 22| overlap or hook over shoulders 22| and prevent disengagement of the teeth while of said members; nat ends on said teeth disposed in aplane nmal to said common axis and l1oin.

ing their working faces along sharp, non-chamfered edges; and said clutch members having predetermined clearances between said teeth when intermeshed; the clutch teeth of one member 

